Proto-oncogenes are normal cellular genes whose activated counterparts, the oncogenes, convert cells in which they are expressed from normal cells to tumor cells. Thus, identification of new proto-oncogenes aid in the understanding, diagnosis, and treatment of cancer. See, e.g., C. Bargmann et al., Detection of Point Mutations in Neu Genes, U.S. Pat. No. 4,935,341 (1990).
D. Young et al., Cell 45, 711-719 (1986), report the identification of a new human oncogene named mas. Unlike other oncogenes, mas is similar to the class of proteins known as G-protein coupled receptors. More recently, G-protein coupled serotonin receptors and G-protein coupled acetylcholine receptors have been shown to induce a neoplastic transformation in fibroblasts transformed therewith. D. Julius et al., Science 244, 1057-1062 (1989); J. Gutkind et al., Proc. Natl. Acad. Sci. USA 88, 4703-4707 (1991). We have previously shown that mutations can be introduced into the .alpha..sub.1 -adrenergic receptor to render it constitutively active, S. Cotecchia et al., Proc. Natl. Acad. Sci. USA 87, 2896-2900 (1990), but it has heretofore been unknown whether adrenergic receptors might also function as proto-oncogenes. The present invention is based upon our ongoing investigations in this area.